Tag Archives: Earth

The uncertainty of science: Scientists studying rocks brought back by the Apollo 14 lunar mission have concluded that one sample originally came from the Earth, and if so would be the oldest known Earth rock.

It is possible that the sample is not of terrestrial origin, but instead crystallized on the Moon, however, that would require conditions never before inferred from lunar samples. It would require the sample to have formed at tremendous depths, in the lunar mantle, where very different rock compositions are anticipated. Therefore, the simplest interpretation is that the sample came from Earth.

The team’s analyses are providing additional details about the sample’s history. The rock crystallized about 20 kilometers beneath Earth’s surface 4.0-4.1 billion years ago. It was then excavated by one or more large impact events and launched into cis-lunar space. Previous work by the team showed that impacting asteroids at that time were producing craters thousands of kilometers in diameter on Earth, sufficiently large to bring material from those depths to the surface. Once the sample reached the lunar surface, it was affected by several other impact events, one of which partially melted it 3.9 billion years ago, and which probably buried it beneath the surface. The sample is therefore a relic of an intense period of bombardment that shaped the Solar System during the first billion years. After that period, the Moon was affected by smaller and less frequent impact events. The final impact event to affect this sample occurred about 26 million years ago, when an impacting asteroid hit the Moon, producing the small 340 meter-diameter Cone Crater, and excavating the sample back onto the lunar surface where astronauts collected it almost exactly 48 years ago (January 31–February 6, 1971).

The scientists also admit that their conclusion is controversial and will be disputed. If true, however, it suggests that there is significant material on the Moon from the early Earth that can provide a window into parts our planet’s history that are presently inaccessible.

Earth’s north magnetic pole has been skittering away from Canada and towards Siberia, driven by liquid iron sloshing within the planet’s core. The magnetic pole is moving so quickly that it has forced the world’s geomagnetism experts into a rare move.

On 15 January, they are set to update the World Magnetic Model, which describes the planet’s magnetic field and underlies all modern navigation, from the systems that steer ships at sea to Google Maps on smartphones.

The most recent version of the model came out in 2015 and was supposed to last until 2020 — but the magnetic field is changing so rapidly that researchers have to fix the model now. “The error is increasing all the time,” says Arnaud Chulliat, a geomagnetist at the University of Colorado Boulder and the National Oceanic and Atmospheric Administration’s (NOAA’s) National Centers for Environmental Information.

Note that they have delayed the release of the World Magnetic Model until January 30, claiming the delay is caused by the government shutdown. Seems bogus to me. As I have already noted, these scientists aren’t slaves. If they think this is so important, and they have completed their work (which the article suggests they have), they can release the model, regardless of the federal government’s funding.

Hat tip reader Stephen Taylor.

Cool image time! The image on the right, cropped and reduced to post here, shows a volcano not on Mars or the Moon or any of the moons of Jupiter or Saturn, but here on Earth in South America!

Llullaillaco is a stratovolcano at the border of Argentina and Chile. It lies on a high plateau close to the Atacama Desert. At an elevation of 6723 m ASL, it is the second highest active volcano in the world. About 150,000 years ago the volcano’s southeastern flank collapsed, producing a debris avalanche that traveled 25 kilometers. The youngest dated rocks are about 5600 years old; but there are local reports of activity from the 1800s. The perspective image looking east was acquired December 19, 2014.

If you click on the link you can see the full image. It was taken by one of the instruments on the Earth-observation satellite Terra, launched in December 1999. Though the website for this image does not state so, I suspect that some of the colors we see here are false colors, as some of the data comes from the infrared.

A new study of a stalagmite in China suggests that the Earth’s magnetic field can reverse polarity in as little as two centuries, not the thousands of years as previously thought.

He and his ANU colleague Dr Xiang Zhao from the Research School of Earth Sciences contributed to the study of the paleomagnetic record from 107,000 to 91,000 years ago that is based on precise magnetic analysis and radiometric dating of a stalagmite from a cave in southwestern China.

The stalagmite, which is one metre in length and eight centimetres in diameter, has a candle-like shape and ranges in colour from yellow to dark brown. “The record provides important insights into ancient magnetic field behaviour, which has turned out to vary much more rapidly than previously thought,” Professor Roberts said.

In the past century or so the Earth’s magnetic field has weakened by about 10%. Some scientists think it possible this presages a possible magnetic reversal, which is apparently overdue. However, up until now it was assumed from available data that any reversal would take thousands of years for the magnetic field to shut down and then restart with a flipped polarity. This new data says the shutdown can happen within the span of one human life.

It is unclear to me if this increases our risk or decreases it. The magnetic field acts to protect us from the solar wind and other space radiation. When it shuts down there will be consequences, many negative, that we now can’t even predict. If a reversal is beginning now but takes longer to happen we will have at least a thousand years to plan and adapt, but the period of shut down will be far longer, causing more harm. If it happens quickly we will have to scramble to adapt, but the period of harm will be very short, and thus might not have time to cause significant harm.

Either way, this result is decidedly uncertain, based on a single stalagmite. No one should take it too seriously without further confirmation from other evidence.

The uncertainty of science: Using computer models and data from the past two changes in the Earth’s magnetic field, some scientists now claim that the weakening of the magnetic field in the past two centuries does not herald an upcoming flip in polarity.

To calculate the likelihood of a full field switch, Holme and his colleagues looked at the magnetic alignment of rock particles deposited in and before the two most recent excursions – the Laschamp event, approximately 41,000 years ago, and the Lake Mono event, which occurred 34,000 years ago.

The scientists found that the strength of the Earth’s magnetic field several thousand years before the two wobbles – at 49,000 and 46,000 years ago – were pretty much the same as they are now. However, they were accompanied by SAA-style weak areas of much greater magnitude.

This, suggests Holme’s teams, considerably reduces the chances of anything drastic happening now. “There has been speculation that we are about to experience a magnetic polar reversal or excursion,” says Holmes. “However, by studying the two most recent excursion events, we show that neither bear resemblance to current changes in the geomagnetic field and therefore it is probably unlikely that such an event is about to happen.

“Our research suggests instead that the current weakened field will recover without such an extreme event, and therefore is unlikely to reverse.”

Can I express my skepticism? This research is interesting, but there is no way it could provide enough data for anyone to trust such a prediction. We have zero knowledge of the behavior of the magnetic field during a polarity switch, and to claim that this data gives us enough information to say that we do understand that behavior is an overstatement of stupendous proportions.

Just as we don’t really understand the mechanics of the Sun’s magnetic field, causing it to flip polarity every 11 years, we certainly don’t understand the Earth’s either. The Earth’s magnetic field is going to do what it is going to do, and when it does, we will then maybe get an inkling as to why it does it.

The uncertainty of science: New research about the Earth’s core contradicts the presently accepted theories about the Earth’s formation.

New geochemical research indicates that existing theories of the formation of the Earth may be mistaken. The results of experiments to show how zinc (Zn) relates to sulphur (S) under the conditions present at the time of the formation of the Earth more than 4 billion years ago, indicate that there is a substantial quantity of Zn in the Earth’s core, whereas previously there had been thought to be none. This implies that the building blocks of the Earth must be different to what has been supposed.

The research suggests that the Earth is made up of materials different than expected, which means that the materials from the solar system from which it formed are different than presently believed, which also means that present formation theories will need to be revised.

The uncertainty of science: New data using date-stamped jars covering the period from the 8th to the 2nd century BC suggest that the 8th century BC was a period when the Earth’s magnetic field was particularly strong, leading the scientists doing the research to conclude that the Earth’s magnetic field might not be weakening and that the recent field strength decline detected in the past two hundred years might simply be part of the field’s normal fluctuations.

This new data is certainly worthwhile, but the press release surely doesn’t reveal how the scientists were able to extrapolate future magnetic field strength from 8th century BC fluctuations. At a minimum, I would need to see a graph showing the measured field strength from the 8th century BC to the present time to see how today’s field strength compares with the past. Unfortunately, the press release does not provide this.

Cool image time! The image above, a composite of four separate Mars Reconnaissance Orbiter pictures, was taken on November 20, 2016.

Each was separately processed prior to combining them so that the moon is bright enough to see. The moon is much darker than Earth and would barely be visible at the same brightness scale as Earth. The combined view retains the correct sizes and positions of the two bodies relative to each other.

The reddish region on Earth is Australia, with Antarctica the bright white area below that.

An evening pause: This video release from NASA made the rounds a few weeks ago. It isn’t news, but it is cool. One important fact noted during this video is that the Earth’s cloud cover both warms and cools the planet. What wasn’t noted was that there is gigantic uncertainty about how much the clouds warm and cool, which is one of the main reasons no climate models have been even close to successfully predicting the climate.

The uncertainty of science: A new analysis of the past strength of the Earth’s magnetic field suggests that today’s field is abnormally strong and that, even with the 10% decline in the field’s strength in the past two centuries, it remains stronger than the average over the past 5 million years.

The new data also suggests that the field might not be about to shut down and then reverse polarity, as some scientists have theorized based on the 10% decline. Instead, the data says that the field’s unusual strength today only means that the decline is bringing it back to its average strength, and is not necessarily an indication of a pending reversal.

To put it mildly, there are a lot of uncertainties here, including questions about the database that has been used previously by geologists to estimate the past strength of the Earth’s magnetic field. The database might have been right, but the new study raises significant new questions.

Cool image time! NASA’s DISCOVR solar observation probe has released its first image of the Earth, taken from its station-keeping position a million miles from Earth.

This camera was originally designed for Al Gore’s proposed propaganda mission where a spacecraft would take daily pictures of the Earth to pound home his environmental agenda. Eventually NASA found a real use for the satellite’s overall structure and location, observing the Sun’s activity and give us advance warning of dangerous flares or coronal mass ejections.

They left the Earth-viewing camera on board, partly because it was built already (it would cost money to remove) and partly because daily images like this can be of some scientific value.

New research attempting to explain why the Earth but not the Moon has so much iron splattered through its mantle has found that iron can be more easily vaporized during impacts than previously thought, and thus rained down on the planet during the early asteroid bombardment.

Principal investigator Kraus said, “Because planetary scientists always thought it was difficult to vaporize iron, they never thought of vaporization as an important process during the formation of the Earth and its core. But with our experiments, we showed that it’s very easy to impact-vaporize iron.” He continued, “This changes the way we think of planet formation, in that instead of core formation occurring by iron sinking down to the growing Earth’s core in large blobs (technically called diapirs), that iron was vaporized, spread out in a plume over the surface of the Earth and rained out as small droplets. The small iron droplets mixed easily with the mantle, which changes our interpretation of the geochemical data we use to date the timing of Earth’s core formation.”

The Moon’s gravity in turn wasn’t sufficient to pull its own iron vapor down. Thus, it does not have much iron in its mantle.

Worlds without end: The existence of a Kepler-found earth-sized planet in the habitable zone has been confirmed.

The newfound planet, called Kepler-186f, was first spotted by NASA’s Kepler space telescope and circles a dim red dwarf star about 490 light-years from Earth. While the host star is dimmer than Earth’s sun and the planet is slightly bigger than Earth, the positioning of the alien world coupled with its size suggests that Kepler-186f could have water on its surface, scientists say.

After the unmanned probe Juno zipped past the Earth on its way to Jupiter today, it unexpectedly went into safe mode.

Engineers continued to diagnose the issue, which occurred after Juno whipped around Earth in a momentum-gathering flyby. Up until Wednesday, Juno had been in excellent health. While in safe mode, it can communicate with ground controllers, but its activities are limited.

I haven’t yet had time to read this special issue, but it will certainly be fascinating, as it apparently summarizes the most current knowledge scientists have about the manner and timing of the human migration of the entire surface of the Earth. Overall, it appears that this migration took place sooner and faster than previously believed. Definitely worth a read.

Duck! The orbit of a 150 foot wide asteroid that zipped past the Earth in February, has an orbit that will bring it past the Earth again on February 15, 2013 by less than 15,000 miles.

The team use several automated telescopes to scan the sky, and the discovery came somewhat serendipitously after they decided to search areas of the sky where asteroids are not usually seen. “A preliminary orbit calculation shows that 2012 DA14 has a very Earth-like orbit with a period of 366.24 days, just one more day than our terrestrial year, and it ‘jumps’ inside and outside of the path of Earth two times per year,” says Jaime.

While an impact with Earth has been ruled out on the asteroid’s next visit, astronomers will use that close approach for more studies and calculate the Earth and Moon’s gravitational effects on it.

Because this newly discovered asteroid passes so close and frequently to both the Earth and Moon, astronomers will need a lot more data before they can pin down its orbit precisely, and thus predict the chances of a collision in the near future.

“Not simply about one mission, [Genesis] is also the history of America’s quest for the moon… Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America’s greatest human triumphs.”
–San Antonio Express-News

Lecture: September 25, 2019, noon (Eastern), for the AIAA Northwest Florida Section at Elgin Air Force Base, Florida. Subject: How Apollo 8 won the 1960s space race and changed the world.

Lecture: September 25, 2019, late afternoon (Eastern). for local middle school children for the AIAA Northwest Florida Section at Elgin Air Force Base, Florida. Subject: Unknown Stories from Space: Astronaut adventures that did not reach the press.

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